Metamorphic Linkage Research Articles

A Kirigami-Inspired Metamorphic Double-Loop Linkage With Multiple Single-Degree-of-Freedom Reconfiguration Branches

Abstract Reconfigurable mechanisms attract increasing attention for the characteristic to change structure configurations and motion behaviors in various multifunctional systems. By drawing inspiration from a kirigami fold, this paper presents a metamorphic double-loop linkage with multiple single-degree-of-freedom (DOF) reconfiguration branches, which is generated through combining two reconfigurable 6R plane-symmetric linkages. Mobility analysis of the metamorphic linkage is carried out in terms of the screw-loop theory equation, as well as the induced reconfiguration position identification. Then, this paper presents the specific reconfiguration conditions for the two single-loop components in this linkage, and a physical prototype fabricated by 3D printing verifies the ability of configuration reconstruction. Sixteen types of evolved motion branches are constructed by implementing different reconfiguration constraints, respectively, and corresponding kinematic paths are described by employing the specific angle between axes of joints. Furthermore, these evolved motion branches of this metamorphic linkage provide novel examples of mobile assemblies among several fundamental single-loop linkages.

Three Novel Symmetric Waldron–Bricard Metamorphic and Reconfigurable Mechanisms and Their Isomerization

This paper explores a class of metamorphic and reconfigurable linkages belonging to both Waldron's double-Bennett hybrid linkage and Bricard linkages, which include three novel symmetric Waldron–Bricard metamorphic and reconfigurable mechanisms, and further presents their three extended isomeric metamorphic linkages. The three novel Waldron–Bricard metamorphic and reconfigurable linkages are distinguished by line-symmetric, plane-symmetric, and line-plane-symmetric characteristics. The novel line-symmetric Waldron–Bricard metamorphic linkage with one Waldron motion branch and two general and three special line-symmetric Bricard motion branches is obtained by integrating two identical general Bennett loops. The novel plane-symmetric Waldron–Bricard reconfigurable linkage with two plane-symmetric motion branches is obtained by coalescing two equilateral Bennett loops. The novel line-plane-symmetric Waldron–Bricard metamorphic linkage with six motion branches is obtained by blending two identical equilateral Bennett loops, including the plane-symmetric Waldron motion branch, the line-plane-symmetric Bricard motion branch, the spherical 4R motion branch, and three special line-symmetric Bricard motion branches. With the isomerization that changes a mechanism structure but keeps all links and joints, each of the three novel Waldron–Bricard linkages results in an extended isomeric metamorphic linkage. This further evolves into the study of the three isomeric mechanisms. The study of these three novel metamorphic and reconfigurable mechanisms and their isomerization are carried out to demonstrate the characteristics of bifurcation and to reveal motion-branch transformation. Furthermore, by exploring the intersection of given motion branches and using the method of isomerization, more metamorphic and reconfigurable linkages can be discovered to usefully deal with transitions among possible submotions.

Novel spherical-planar and Bennett-spherical 6R metamorphic linkages with reconfigurable motion branches

A metamorphic linkage is capable of changing its motion branches and can be used as mechanisms for reconfigurable robots for various tasks. This paper presents two novel metamorphic linkages as the spherical-planar 6R metamorphic linkage and the Bennett-spherical 6R metamorphic linkage both of which have three various distinguished motion branches. Having established the close-loop equation of the spherical-planar 6R metamorphic linkage, the paper reveals the conditions of various motion branches and a set of transformations for switching motion branches. The paper further uses to reveal the inherent properties of this over-constrained metamorphic 6R linkage that is able to perform both spherical and planar motion with mobility one. Because of geometrical constraints at bifurcation points, the linkage is able to reconfigure to the deployed spherical motion branch, the planar motion branch and the folded spherical motion branch. The two spherical motion branches could be seen on both a large sphere that presents the deployed spherical motion and a small sphere that presents the folded spherical motion. This leads to the revelation of the novel Bennett-spherical 6R metamorphic linkage that has the transition from one deployed Bennett configuration branch to a spherical configuration branch and then to another folded Bennett configuration branch. Given the geometric parameters of both metamorphic linkages, it reveals that these linkages are special cases of Bricard line-symmetric 6R linkage.

Nihilistic light entertainment and metamorphic linkages: dada and contemporary comedy

ABSTRACTThis article traces the metamorphic linkages between the performances of the early twentieth century Dada movement and their continuation in a form of ‘nihilistic light entertainment’ evident within contemporary comedy. The Dadaists’ preferred style of fusing music and a form of comedy was a key element of their ‘Cabaret Voltaire’. This synthesis was a peculiar performative experiment central to the German Expressionist artistic cabaret. This article posits that the Dadaist cabaret formula has been incorporated into the work of some contemporary comedians. In the UK, the alternative comedy movement in the 1980s spawned a mainstream TV incarnation, the post-modern music hall act of Reeves and Mortimer. Contemporaneously, in the US, the Dada Cabaret's meld of performance art, stand-up comedy and music is evident in the improvisations and apparent spontaneities (the non sequiturs and incongruities) employed by comedians: Zach Galifianakis, Reggie Watts and Eric Andre. In embracing the comedic style of the Cabaret Voltaire, these artists apply music as an artistic device within their performance work. In this article, these metamorphic linkages, along with notions of how improvisation and spontaneity also featured within the Dada's anarchic aleatory art experimentations will be evaluated to position the idea of neo-Dadaist strain within modern comedy.

Structure synthesis of reconfigurable parallel mechanisms with closed-loop metamorphic linkages

This paper proposes a class of closed-loop metamorphic linkages, which has different phases resulting from links annexing or locking of motors. Reconfigurable limbs are obtained by assembling these metamorphic linkages with kinematic chains. The potential metamorphic linkages are presented and the working phase transformation of the metamorphic linkages is analyzed. After adding suitable kinematic joints to the metamorphic linkage, the reconfigurable limbs whose constraint can be switched among different constraint forces and couples are synthesized. The serial limbs that can provide u ( u = 0, 1, 2) constraint forces and v ( v = 0, 1, 2) constraint couples are constructed by using screw theory method. The reconfigurable limbs which possess different configurations are combined with serial kinematic chains. By connecting the end moving platform to the fixed base with three identical kinematic limbs, a family of reconfigurable mechanisms with closed-loop metamorphic linkages is derived. These mechanisms have various output motion modes, such as 3R, 1T2R, 2T1R, and 3T.

A class of reconfigurable parallel mechanisms with five-bar metamorphic linkage

This paper presents a planar five-bar metamorphic linkage which has five phases resulting from locking of motors. Reconfigurable limbs are constructed by integrating the five-bar metamorphic linage as sub-chains. The branch transition of metamorphic linkage is analyzed. By adding appropriate joints to the planer five-bar metamorphic linkage, reconfigurable limbs whose constraint can switch among no constraint, a constrained force and a constrained couple are obtained. Serial limb structures that can provide a constraint force and a constraint couple are synthesized based on screw theory. Reconfigurable limbs that have five configurations associated with the five phases of the five-bar metamorphic linkage are assembled with 4-DOF (degrees-of-freedom) serial chains. A class of reconfigurable parallel mechanisms is derived by connecting the moving platform to the base with three identical kinematic limbs. These parallel mechanisms can perform various output motion modes such as 3T, 3R, 2T1R, 1T2R, 3T1R, 2T2R, 1T3R, 2T3R, 3T2R and 3T3R. Finally, the potential application of the proposed mechanisms is analyzed and conclusions are drawn.

Reconfigurable parallel mechanisms with planar five-bar metamorphic linkages

This paper presents the idea of constructing reconfigurable limbs by integrating metamorphic linkages as subchains. The planar five-bar metamorphic linkages that have three phases resulting from locking of motors are considered. Under the assumption that the constraint exerted by the reconfigurable limb can switch between no constraint, a constraint force, and a constraint couple, the output motions of the metamorphic linkage in its two planar four-bar linkage phases are identified. By adding an appropriate joint to planar four-bar linkages with translational output, four planar five-bar linkages that can be employed in the construction of reconfigurable limbs are enumerated. Serial chains that can provide a constraint couple and a constraint force are synthesized based on screw theory. Reconfigurable limbs that have three configurations associated with the three distinct phases of the metamorphic linkages are assembled with planar five-bar metamorphic linkages and serial chains with four degrees of freedom. A class of reconfigurable parallel mechanisms are constructed by connecting a moving platform and a base with three identical reconfigurable limbs. The degrees of freedom of the reconfigurable parallel mechanism in different configurations with the metamorphic linkages in different phases are given. Finally, the actuation scheme for this kind of mechanisms is addressed.

A constraint graph representation of metamorphic linkages

A metamorphic linkage has the property that the effective number of links and joints can change during the movement of the device. This means the kinematic structural representation of a metamorphic linkage has different forms in which vertices and edges combine depending on the configuration of the device. In this paper, we use the constraint graph of computational geometry rather than the traditional topological graph to characterize a metamorphic linkage in order to simplify the representation of its configuration changes. A constraint graph has geometric elements as vertices and their relationships as edges. We find that the adjacency sub matrix of the constraint graph provides a convenient description of changes in the topology of links and joints in the operation of the metamorphic linkage. Operations on the adjacency submatrix capture topological changes in a metamorphic linkage. We illustrate our results with several examples.

Mathematical Analysis of Finger Positions of a Spherical Linkage Metamorphic Robot Palm

Grasping is the main function performed by the mechanical hand. Mechanisms with more functionality are needed for secure grasping of different and complex objects. With the advancement of the field of robotics it is important to think of mechanisms of multifingered robot hand with added functionality. The metamorphic mechanism with spherical linkage opens a wide opportunity to design a multi fingered robot hand with spherical palm, which can achieve human like dexterity. On the basis of an intensive study of literature, this paper focuses on the development of a geometrical model and mathematical analysis of spherical robot palm with fingers attached to it. To develop the generalised mathematical model, the co-ordinate transformation matrices of the joint axis position and the finger position have been derived. The transformation matrices have been derived with the position and orientation of the links and finger positions. So the co-ordinate points of a point of interest in the three dimensional space can be described at different configuration state of the mechanism. The detail analysis has been done through this mathematical and geometrical modelling of five-bar spherical metamorphic linkage robotic palm. This mathematical and geometrical model can be used to inspect the feasibility of the mechanism design for a multi fingered robot palm. Journal of Mechanical Engineering Vol.36 Dec. 2006 pp.18-26DOI = 10.3329/jme.v36i0.807